Chapter 4：Data processing

Data processing

1. A suite of techniques process and manipulate sequential data streams efficiently.

2. Extend the concept of sequential data to include collections that have unbounded or even infinite size

Implicit Sequences

 an example of lazy computation：range

 lazy computation describes any program that delays the computation of a value until that value is need

Iterators

An iterator is an object that provides sequential access to values, one by one.